This invention relates to a device for controlling and monitoring the thickness of a chocolate film delivered by chocolate refiners.
As is known in the art, chocolate refiners are machines which comprise essentially a plurality of rollers successively carried for adjustable displacement to and from each other in a supporting frame or stand, to permit the gap between any one roller and the following roller to be adjusted. In this respect, the roller push-aside gap that the material being entrained may create decreases gradually from the input roller pair, arranged side-by-side to form an input chamber, and the last roller pair in the refiner, the last roller being the output or delivery roller. The delivery roller is wrapped over most of its circumference, e.g., 3/4 of its circumference, with the chocolate film being delivered, which will leave said roller onto a doctoring blade associated with the delivery roller. The required chocolate film thickness may vary within a wide range, in general values of 15 to 30 .mu.m being those required. Thus, the thickness dimensions handled are very small ones, and are dependent on the thickness dimensions of solid particulates of cocoa, sugar, milk, etc. contained in the film, which comprises, in a conventional manner, a mixture of cocoa, sugar, fatty substance or cocoa butter, milk, and so on. It will be apparent that this mixture is a heterogeneous one through the film of chocolate being delivered, the distribution of the individual ingredients per surface area unit occurring differently and irregularly in a random fashion. With prior refiners, the rollers which are located downstream of the input roller pair have a velocity which increases toward the output roller. This results in a squeezing and entraining action being applied on the chocolate mass to form a filn of decreasing thickness toward the output roller.
In order to resist undesired thickness deviations in the chocolate film being delivered, prior refiners provide for the bearing pressure therebetween to be changed, more specifically the bearing pressure from the input pair to the rollers downstream thereof. This may be achieved substantially in either of two ways, namely, by changing the bearing pressure on all the bearings of the refining rollers, or alternatively, by changing the bearing pressure on individual bearings of said refining rollers, the latter approach enabling the bearing pressure to be varied individually between the rollers. In all cases, the main adjustment is effected on the input roller pair, because, with the refiner in a steady state of operation, the amount per unit of time of the chocolate mass being fed must correspond to the amount by weight of the film being delivered.
No detailed description of the roller bearing pressure adjustment systems in such refiners will be given herein, because the device of this invention may be equally useful with any such pressure adjustment systems.
With all of the conventional refiners, irrespective of the more or less sophisticated construction of such systems for adjusting the pressure acting on the bearings of the refining rollers, the problem is encountered of how to measure the actual thickness of the film of chocolate being delivered. That measuring faculty is, however, much needed since a uniform thickness of the chocolate film is indispensable to subsequent processing thereof.
But since it is not possible to measure the chocolate fillm thickness in any direct manner, on account of the film having, on the one side, a very thin slurry-like consistency, and on the other side being kept moving onto a transporting surface (roller), it is current practice to check the thickness or fineness of the chocolate film in the laboratory by using a set of sifters in accordance with coded standards by OICC. However, the latter approach is far from satisfactory, because, on the one hand, it does not afford continuous measuring, and on the other hand, it yields measurement results only after a considerable time on the order of several hours. In fact, at production plants, such laboratories are usually located remote from the production areas, and completion of the measuring operations is time-consuming. Further, in the event of the results requiring an adjustment operation, even after such an adjustment has been carried out--mostly in an empirical fashion--a cross-checking measurement is to be taken again to assess the successful operation. Since such corrections require a number of operations, it will be appreciated that the correction time is quite a long one, while large amounts of chocolate are produced in the meantime which have a different fineness from the nominal or desired fineness.
With conventional refiners, moreover, supervision by an operator becomes necessary to prevent the appearance of solid fragments, such as the so-called "milk patches", or any small pieces of dried fruit shells accidentally dropped into the chocolate paste being fed from resulting in well-known serious seizing of the refiner. Such solid particles, in fact, would come to contact the feeder rollers, and unless taken in and passed over, would lay against the rollers and form an obstruction to the admission of the product onto the rollers with attendant formation thereon of peripheral band areas of absent product, and accordingly dry, which may be several millimeters wide. At such "dry" band areas the rollers are rapidly heated, thus leading to local expansion thereat, said rollers being in mutual contact at said areas. This quickly results in additional heating due to the different roller velocities of rotation, and within a few minutes, in roller seizure.